(1) Field of the Invention
The present invention relates to an in vitro method for asexually propagating corn plants in vitro into a fertile corn plant. In particular the present invention relates to the use of 2,4-dichlorophenoxyacetic acid (2,4-D) or N.sup.6 -benzyladenine (BA) and mixtures thereof to produce differentiated corn tissue from shoot tips or apices and then growing the differentiated tissue in indole-3-butyric acid (IBA) composition to produce the corn plant.
(2) Prior Art
An efficient and reproducible in vitro technique permitting the production of whole plants from transformed cells is an integral part of successful genetic engineering of plants (Vasil, I. K., BioTechnology 8, 296-31 (1990); and Potrykus, I., Physiol. Plant. 79, 125-134 (1990)). Currently, immature zygotic embryos are the most reliable explant source to develop regeneratively-competent calli, cell suspensions and protoplasts for transformation of corn (Rhodes, C. A., Pierce, D. A., Mettler, L. J., Mascarenhas, D., and Detmer, J. J., Science 240, 204-207 (1988); Fromm, M. E., Morrish, F., Armstrong, C., Williams, R., Thomas, J., Klein, T. M., BioTechnology 8, 833-839 (1990); and Gordon-Kamm, W. J., Spencer T. M., Manganno, M. L., Adams, T. R., Daines, R. J., Willets, N. G., Rice, T. B., Mackey, C. J., Krueger, R. W., Kaush, A. P., Lamaux, P. G., Plant Cell 2,603-608 (1990)).
Plant regeneration through somatic embryogenesis has been routinely achieved in Zea mostly from in vitro cultures of 1-2 mm long immature zygotic embryos excised precisely 10-15 days after fertilization (Springer, W. D., Green, C. E., Kohn, K. A., Protoplasma 101, 269-281 (1979); Vasil, V., Lu, C., Vasil, I. K., Protoplasma 127, 1-8 (1985); Duncan, D. R , Williams, M. E., Zehr, B. E., Widholm, J. M , Planta 165,322-332 (1985); Hodges, T. K., Kamo, K. K., Imbrie, C. W., Becwar, M. R., BioTechnology 4, 219-223 (1986)). Cultures of tassel primordia (Rhodes, C. R., Green, C. E., Phillips, R. L., Plant Sci 46, 225-232 (1986)), mature seed embryos (Wang, A., Plant Cell Rep. 6, 360-362 (1987)), and leaf segments (Conger, B. V., Novak, F. J., Afza, R., Erdelsky, K., Plant Cell Rep. 6, 345-347 (1987)) of corn have also regenerated plants through somatic embryogenesis.
What is needed is a method for producing mature corn plants using an asexual, genotype-independent reproduction, wherein the plants are fertile.